Improve Logger type signatures related to level.

[myronmarston]

As shown in the current docs, level can be a String, Symbol, or Integer:

https://github.com/ruby/ruby/blob/b180ffa62270dc32bb69167822b4c698def5c8f7/lib/logger.rb#L388-L393

[ksss]

How about using _ToS interface?

https://github.com/ruby/ruby/blob/232e2f598103c8eda37d08913665b72b6f787e3f/lib/logger.rb#L401

[myronmarston]

How about using _ToS interface?

https://github.com/ruby/ruby/blob/232e2f598103c8eda37d08913665b72b6f787e3f/lib/logger.rb#L401

If I used that, then I believe code like this would type check:

logger = Logger.new("some/file.log", level: Object.new)
logger.level = Object.new

In fact, any object that implements to_s (which everything does except things that inherit directly from BasicObject, IIRC) would type check, but runtime errors will usually result.

An exception is thrown if the string returned by to_s, when downcased, doesn't exactly match one of debug, info, warn, error, fatal or unknown. As a general rule, the only types on which to_s returns a string that will match one of those are String and Symbol. Of course, someone could override to_s on their custom type to have it return one of those values (or someone can monkey patch a built-in type to have it return one of those values...) but in practice I've never seen anyone do that.

In short, while the line you linked to does use .to_s, I believe it does that because it's the "least effort" way to make the method support strings or symbols, not because it intends (or expects) to support any arbitrary object that implements to_s.

[ksss]

@myronmarston You are right.

The _ToS interface is too broad and the current definition is too narrow.
There is a way to specify literals, but it is downcase and there are too many combinations.
The patch way would be a good balance.

---

I found the original discussion.

ruby/ruby#1101
https://bugs.ruby-lang.org/issues/11695

support symbol and string log level setting

It is clear from this that only String and Symbol are intended.